import java.util.Scanner;

public class Main1429 {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int n = sc.nextInt();
        int[] arr = new int[n];
        for (int i = 0; i < arr.length; i++) {
            arr[i] = sc.nextInt();
        }
        int a = 0;
        int b = 0;
        for (int j : arr) {
            if (j >= 90) {
                a++;
            } else if (j < 60) {
                b++;
            }
        }
        if (b != 0) {
            System.out.println("no");
        } else if (a >= 5) {
            System.out.println(1);
        } else if (a == 3 || a == 4) {
            System.out.println(2);
        } else if (a == 2) {
            System.out.println(3);
        }else {
            System.out.println("no");
        }
    }
}
